This invention pertains to friction stir welding and friction stir welded assemblies. More particularly, this invention pertains to stir welded T-joints connecting relatively thin rib members to relatively thin sheet portions of material.
Friction stir welding provides advantages over other methods of welding. Perhaps the most significant advantage is that friction stir welds maintain a significant percentage of the strength associated with the material of the welded members. This allows for strong welded joints without requiring subsequent annealing and heat treating. Thus, in situations where an assembly cannot be annealed and/or heat treated friction stir welding may be the only acceptable method of welding such an assembly.
Despite these advantages, there are also several disadvantages associated with friction stir welding. One such disadvantage is that the stir welding tool utilized to form a stir weld exerts an appreciable amount of force against the assembly during the stir welding process. Thus, this force must be reacted by the assembly and the assembly must be sufficiently strong and rigid so as to avoid breakage and/or unacceptable deflection. Another disadvantage is that the movement of the stir welding tool relative to the components of the assembly can cause undesirable movement of the components relative to each other. Yet a further disadvantage is that relatively precise movement of the stir welding tool is required during welding and, as a result, this movement must generally be automated using complex machinery such as CNC vertical or multi-axis milling machines.